This invention relates to automatic setup of an oscilloscope or similar instrument, and more particularly to such a setup function that is continually responsive to the type of input signal and which provides user choices that anticipate the user""s needs based on characteristics of the input signal. Multiple signal views are associated into a set of signal views, each member of said set being operatively connected for easy access for other members of the set.
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Prior art oscilloscopes with automatic setup functions were sometimes limited in usefulness by the difficulty of getting from one appropriate view to another. A new paradigm of oscilloscope operator interface control is needed, a paradigm that provides instant connectivity and transport between different signal views within a set of related views.
Oscilloscopes have for some time been able to automatically determine vertical gain, vertical position, trigger level and horizontal time scale settings in response to simple signal inputs, such as a sine wave or square wave. However, the effectiveness of these automatic settings was sometimes compromised by the need to make assumptions about the nature of the input signal.
Oscilloscopes typically power-up to a xe2x80x9cfactoryxe2x80x9d or xe2x80x9cpower-upxe2x80x9d setup. Doing so serves several functions. This will typically be a frequently used setup, and therefore has some chance of being at or close to a suitable setup for what the user presently wants to do. Even if it is not, it provides a stable starting point for further work. Having a stable starting point that the user becomes familiar with, enables a user to make rapid and minimal adjustments to get to the desired setting for the present task, assuming that no known saved setting is a closer starting point. If the oscilloscope is shared with other users, it is often desirable for the present user who finds the scope already turned on to initially go to the factory setting to make sure that the instrument is not in some strange mode left by the last user. This assumes that the power-up setup is among the stored setups available to recall, otherwise the same result will require turning the power off and on again. It is also useful to have an oscilloscope power-up to a known state for use in remote-programmed or remote-controlled situations. This allows the remote controlling program or operator to only send changes from the initial state, as opposed to having to send a command for every possible controllable parameter in order to ensure that the final state of the instrument is known.
Originally, the automatic function was limited to initial setup, and it ended its routine once that setup was achieved and the user took over. More recently, however, the automatic function on some oscilloscopes continued controlling the setup during operation, although such a mode is usually optional and may be shut off by the user. Within parts of the industry, this feature is known as xe2x80x9cauto-rangingxe2x80x9d or xe2x80x9ccontinuous setupxe2x80x9d, so as to be distinguishable from the xe2x80x9cauto-setupxe2x80x9d in which the setup parameter control terminated after the initial setup. An auto ranging oscilloscope responds to simple changes in a simple input by modifying its horizontal sweep setting, its vertical gain setting, or, in some cases, even its trigger level settings, in response to the changed inputs.
U.S. Pat. No. 5,155,431 to Holcomb for xe2x80x9cVery Fast Autoscale Topology for Digitizing Oscilloscopesxe2x80x9d, hereby incorporated by reference, describes an oscilloscope that can quickly achieve an appropriate setup by finding the signal maximum and signal minimum through the utilization of peak detection circuitry. U.S. Pat. No. 5,397,981 to Wiggers for xe2x80x9cDigital Storage Oscilloscope with Automatic Timebasexe2x80x9d, hereby incorporated by reference, describes an oscilloscope that can adjust its timebase during operation to keep a constant number of cycles on the screen, even in the presence of a change in frequency of the input signal. Additionally, and apparently for the same type of application, the time axis of the display of this oscilloscope may be labeled in degrees per division instead of time per division.
Some oscilloscopes of the prior art have had the capability of making one or more automated measurements on a simple input signal, such as a sine wave or square wave. These measurements, which had to be selected by an operator, could include frequency (or period), duty cycle, peak-to-peak amplitude, or rise and fall times. For example, U.S. Pat. No. 4,362,394 to Menlove for xe2x80x9cTime Interval Measurement Arrangementxe2x80x9d, hereby incorporated by reference, describes a method and apparatus to make accurate measurements on a complex repetitive waveform.
U.S. Pat. No. 4,779,044 to Skolnick et al. for xe2x80x9cVoltage, Current and Frequency Measuring of Non-standard Waveformsxe2x80x9d, hereby incorporated by reference, describes one way that the period of a regular binary signal can measured by sensing transitions and using a counter to determine the interval between them.
U.S. Pat. No. 4,271,391 to Kmetz for xe2x80x9cDigital Voltmeter with Electro-Optical Indication of the Waveformxe2x80x9d, hereby incorporated by reference, discloses a digital voltmeter that displays a waveform at maximum available vertical amplitude and also displays that voltage level as a numerical value.
U.S. Pat. No. 4,716,345 to Shank et al. for xe2x80x9cAutomatic Pulse Displayxe2x80x9d, hereby incorporated by reference, describes a method for using two trigger detection circuits to trigger at the same level on opposite slopes of a pulse waveform. This provides a way to calculate the duty cycle of the waveform and position it on the screen. This oscilloscope can automatically expand and display an otherwise narrow pulse in the signal input to make the positive portion fill most of the display. This is convenient when a pulse type signal has a very low duty cycle (percentage of total period of the signal wherein the signal is in its xe2x80x9chighxe2x80x9d state.)
U.S. Pat. No. 5,637,994 to Carder for xe2x80x9cWaveform Measurementxe2x80x9d, hereby incorporated by reference, discloses a way to measure the features of a waveform with indeterminate, i.e., variable, arrival times. The time between separate threshold crossings is measured as one of the threshold points is moved. This allows a point-by-point reconstruction of a repetitive waveform occurring at variable intervals.
U.S. Pat. No. 4,985,844 to Foley, et al. for xe2x80x9cStatistical Waveform Profiler Employing Counter/Timerxe2x80x9d, hereby incorporated by reference, describes an oscilloscope system that repetitively performs pulse width measurements, and to enable this feature the system automatically determines suitable resolution and offset settings. U.S. Pat. No. 5,155,431 to Holcomb for xe2x80x9cVery Fast Autoscale Topology For Digitizing Oscilloscopesxe2x80x9d, hereby incorporated by reference, describes an oscilloscope with dedicated peak detector hardware that operates in conjunction with a trigger counter to rapidly set the vertical scale and offset and the horizontal sweep rate.
Histograms provide a powerful tool for waveform analysis and instrument control. U.S. Pat. No. 4,985,844 to Foley et al. for xe2x80x9cStatistical Waveform Profiler Employing Counter/Timerxe2x80x9d, hereby incorporated by reference, describes a histogram-based counting arrangement that makes measurements on repetitive input signals and uses the results as the basis for the generating a histogram. Histograms can also provide a basis for automated measurements, although more slowly than with some of the specialized approaches described elsewhere herein.
U.S. Pat. No. 5,495,168 to deVries for xe2x80x9cMethod of Signal Analysis Employing Histograms to Establish Stable, Scaled Displays in Oscilloscopesxe2x80x9d, hereby incorporated by reference, describes an oscilloscope system that uses both amplitude histograms and time histograms. The amplitude histogram method is used first to determine the minimum and maximum amplitude levels of the signal. Then a time histogram method is used to determine predominant time intervals occurring in the input signal.
U.S. Pat. No. 5,003,248 to Johnson for xe2x80x9cProbability Density Histogram Displayxe2x80x9d, hereby incorporated by reference, discloses an oscilloscope that optionally provides a probability density histogram alongside the conventional voltage-versus-time time-domain display of the waveform. U.S. Pat. No. 5,343,405 to Kucera at al. for xe2x80x9cAutomatic Extraction of Pulse Parameters from Multi-valued Functionsxe2x80x9d, hereby incorporated by reference, shows how histograms can keep track of the occurrence of eye-pattern data over multiple acquisitions. Pulse parametrics defining various aspects of the signal under test can be determined from these histograms, which are in effect adding a third dimension to the display.
U.S. Pat. No. 5,793,642 to Frisch et al. for xe2x80x9cHistogram based testing of analog signalsxe2x80x9d, hereby incorporated by reference, describes how reference histograms can provide a quick and data efficient way to compare acquired waveform information with a reference waveform and rapidly communicate the results using limited information bandwidth. U.S. Pat. No. 5,122,996 to Sasaki et al. for xe2x80x9cReal-Time Uninterrupted Time-Interval to Voltage Converterxe2x80x9d, hereby incorporated by reference, describes an oscilloscope-related feature that allows the viewing of signal periods as voltages, even while such periods and resulting voltages are changing from cycle to cycle.
U.S. Pat. No. 5,397,981 to Wiggers for xe2x80x9cDigital Storage Oscilloscope With Automatic Time Basexe2x80x9d, hereby incorporated by reference, describes an oscilloscope system in which the operator makes a selection with regard to the horizontal axis and number of signal cycles desired, and an appropriate display is produced and maintained. U.S. Pat. No. 4,743,844 to Odenheimer, et. al., for xe2x80x9cSelf-adjusting Oscilloscopexe2x80x9d, hereby incorporated by reference, describes an oscilloscope system in which the vertical amplifier gain and offset, the trigger level, and the sampling rate of the digitizer can be automatically controlled in response to the input signal.
Certain specialized oscilloscope-like instruments are either built to, or may be programmed to, respond appropriately to more complex inputs, e.g., a television video signal. U.S. Pat. No. 5,027,058 to Kleck et al. for xe2x80x9cMulti-standard Video Option for Oscilloscopesxe2x80x9d, hereby incorporated by reference, describes an oscilloscope that can determine which video standard a television video signal is compliant with, and set up the horizontal sweep accordingly. The type of horizontal sync pulse, bi-level or tri-level, and the width or number of lines per frame are used in making the determination of which video standard is being used.
The Tektronix TDS300, as well as the oscilloscopes offered by some competitors, also provides FFT (fast Fourier transform) waveform analysis so as to combine in one instrument some of the power of a spectrum analyzer as well as a conventional oscilloscope. Such built-in harmonic (frequency)-based displays proved useful in power supply design and communications applications, anywhere that a power-versus-frequency view of the signal would augment insight.
U.S. Pat. No. 5,375,067 to Berchin for xe2x80x9cMethod and Apparatus for Adjustment of Acquisition Parameters in a Data Acquisition System such as a Digital Oscilloscopexe2x80x9d, hereby incorporated by reference, discloses another digital oscilloscope that also analyzes the signal in the frequency domain. To maximize performance, this oscilloscope automatically adjusts the acquisition parameters to optimal values for a particular repetitive waveform. The acquisition parameters are adjusted such that the sampling rate is sufficient to avoid aliasing of the highest significant frequency components of the input waveform while accommodating all or substantially all of the waveform within the waveform memory capacity.
U.S. Pat. No. 4,802,098 to Hansen et al. for xe2x80x9cDigital Bandpass Oscilloscopexe2x80x9d, hereby incorporated by reference, describes an oscilloscope that is capable of simultaneously displaying both a time domain waveform and a frequency domain spectrum. The bandwidth of the passband is automatically adjusted to minimize aliasing in the time domain display.
U.S. Pat. No. 5,138,252 to Ferguson for xe2x80x9cAutomatic Scaling for Display of Modulation Domain Measurementsxe2x80x9d, hereby incorporated by reference, describes a method for examining an input signal and setting a modulation domain measuring instrument to a state which will produce a measurement and a stable, centered, properly scaled display of the signal automatically.
U.S. Pat. No. 5,081,592 to Jenq for xe2x80x9cTest System for Acquiring, Calculating and Displaying Representations of Data Sequencesxe2x80x9d, hereby incorporated by reference, describes an electronic device testing system having an additional capability of performing any one of a set of mathematical operations on a data sequence and displaying the resulting waveform in a new window.
Oscilloscopes currently on the market allow the operator to trigger on pulses defined by amplitude (such as runt pulses), logic state or temporal pattern, or events qualified by time, e.g., pulse width, glitch, slew rate, setup-and-hold, or time-out. Combinations of extended and conventional triggers also help display video and other difficult-to-capture signals. Advanced triggering capabilities such as these deliver a large degree of flexibility when setting up testing procedures and can greatly simplify measurement tasks. Moreover, software is now available in the marketplace that automates and simplifies power measurement, jitter analysis, and disk drive measurement.
In some more recent oscilloscope user interfaces, by using vertical and horizontal scale knobs or a mouse the user can see the signal waveform with more magnification or compression. A xe2x80x9czoomxe2x80x9d feature can have both xe2x80x9czooming inxe2x80x9d and xe2x80x9czooming outxe2x80x9d, with xe2x80x9czooming inxe2x80x9d being magnification and xe2x80x9czooming outxe2x80x9d being compression. This function can be controlled by drawing a box around a feature of interest in one waveform, e.g., by using a mouse, and then seeing the boxed portion of that waveform expanded for a more detailed view in another vertical location.
One oscilloscope manufacturer allows up to eight different views of waveforms stacked vertically, i.e., full length but reduced height. These can contain views of up to four different channels, combinations of those channels as processed by a math function calculator, and zoom window magnification or compression. Each of these views must be set-up by the operator and all are at least partially correlated with each other in the horizontal (time) dimension. Some oscilloscopes have long provided the capability of displaying an xe2x80x9cXYxe2x80x9d display, as well as conventional amplitude-versus-time (YT) display. An XY display shows one signal as a function of the other (instead of as a function of time).
Modern digital oscilloscopes typically provide some means for the user to save and label a setup that it may be desirable to return to. This can save the operator""s time with frequently used setups and avoid needless confusion or memorization of how to reach relatively obscure or infrequently used setups. These modern oscilloscopes typically offer a variety of setup choices in menu form, and may have some version of the xe2x80x9cautosetxe2x80x9d or xe2x80x9cauto-rangexe2x80x9d feature described at some length above. As has also been discussed above, many digital oscilloscopes on the market today are capable of performing automatic measurements of various kinds. At least one manufacturer provides measurement icons that can be dragged over a waveform feature, causing the oscilloscope to then make the measurement indicated by the icon.
The operator doesn""t see a rendition of how the waveform will look., but rather is presented with an icon and instant or delayed labeling. Delayed labeling may be like the xe2x80x9cToolsTipsxe2x80x9d-type, the type wherein the function is described in words, abbreviations, acronyms that only appear when a cursor stops moving and is resting on an icon. To use this feature, the operator has to understand which measurement a particular icon may be intended to represent. The operator usually doesn""t see a realistic rendition of how the next waveform view will look in that view. This interface can be constructed so that if a cursor lingers on it, permanent messages can be augmented by xe2x80x9cpop-upxe2x80x9d temporary messages.
What is desired is a different and more graphic and helpful way to continually present the oscilloscope operator with setup choices and convenient paths to other views.
Multiple views of the signal are generated by a time-sharing use of the oscilloscope""s acquisition hardware. The instrument software makes a set of measurements of the input signal, and from the results of those measurements classifies the input signal as to type. Signals of particular types implicitly select suites of views of the signal. The operator sees examples of the other views available while a related view is the main view. The initial main view is the first recommendation for this type of signal. It is shown relatively large and in detail, with measured values displayed on the screen. Alternate views, which may be shown as xe2x80x9clivexe2x80x9d miniature views, are displayed, perhaps in simplified form, alongside the main view. By clicking on them, these alternative views may be made to become the main view. The operator can add and modify views.
Each view comes with a set of measurements that are automatically performed and displayed on the screen with the waveform. These pre-selected measurements are performed immediately and automatically, thereby usually meeting the operator""s needs without requiring any actions on his part. The oscilloscope software also tries to anticipate and present one or more alternative setups that the user might prefer. A different view of the signal comes with different automatic measurements, and presents the results of these measurements as annotations to the waveform image. These next alternative setups may be made available on a conventional menu list, or displayed at a reduced size, either as static icons or miniature xe2x80x9clivexe2x80x9d displays. The xe2x80x9clivexe2x80x9d version of these icons can show the user exactly what a next available display will look like, while keeping the emphasis on the presently displayed setup by showing it in a relatively maximum size view.